Abstract
Transcutaneous auricular Vagal Nerve Stimulation (taVNS) is a non-invasive brain stimulation technique associated with possible modulation of norepinephrinergic (NE) activity. NE is suspected to contribute to generation of the P3 event-related potential. Recent evidence has produced equivocal evidence whether taVNS influences the P3 in healthy individuals during oddball tasks. We examined the effect of taVNS on P3 amplitudes using a novel visual Bayesian oddball task, which presented 200 sequences of three stimuli. The three consecutive stimuli in each sequence are labelled Draw 1, Draw 2 and Draw 3. In total, 47 Subjects completed this visual Bayesian oddball task under randomised sham and active taVNS stimulation in parallel with an electroencephalographic (EEG) recording. We conducted exploratory analyses of the effect of taVNS on P3 amplitudes separately for Draws. We found typical oddball effects on P3 amplitudes at Draws 1 and 2, but not Draw 3. At Draw 2, the oddball effect was enhanced during active compared to sham taVNS stimulation. These data provide evidence that taVNS influences parietal P3 amplitudes under specific circumstances. Only P3 amplitudes at Draw 2 were affected, which may relate to closure of Bayesian inference after Draw 2. Our findings seemingly support previously reported links between taVNS and the NE system.
Highlights
The vagus nerve is an autonomic nerve which regulates major organs and physiological responses [1]
Given the limited nature of the literature, we developed a particular version of the Bayesian oddball task [44] to provide clarity on mechanisms of Transcutaneous auricular vagal nerve stimulation (taVNS), using more specific situations under which the P3 can be observed. taVNS may have value as a method of brain stimulation, as its non-invasive nature and quick application make it an ideal tool for use in behavioural studies or potential therapies
We report the findings from the time-window of 400 ms–449 ms (Figure 4), as this returned the most interesting effects of taVNS from inferential statistical analysis and previous studies focused on similar epochs for active oddball variants [60,61]
Summary
The vagus nerve is an autonomic nerve which regulates major organs and physiological responses [1]. Invasive vagal nerve stimulation (VNS) has been used as a treatment for disorders such as epilepsy and depression [2,3,4,5], the success of which has been attributed to possible activation of the. The LC is innervated by the solitary tract, a brainstem nucleus for vagus nerve afferents [9,10] and lesions to this region abolish the therapeutic effects of VNS in both depression and epilepsy [11,12,13]. The auricular branch of the vagus nerve supplies the cymba conchae (i.e., the inner part of the auricle [18,19]), as well as the tragus [20,21,22].
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